MKSAP Quiz: 6 months of exertional dyspnea
A 46-year-old man is evaluated for 6 months of exertional dyspnea, fatigue, and ankle edema. Recently he experienced near-syncope walking up two flights of stairs. He has no other medical problems and takes no medications. Following a physical exam, transthoracic echocardiogram, and other tests, what is the most appropriate treatment?
A 46-year-old man is evaluated for 6 months of exertional dyspnea, fatigue, and ankle edema. Recently he experienced near-syncope walking up two flights of stairs. He has no other medical problems and takes no medications.
On physical examination, blood pressure is 106/70 mm Hg, pulse rate is 94/min, and respiration rate is 18/min. Oxygen saturation is 90% breathing ambient air. On cardiac examination, a prominent jugular venous a wave is present along with widened splitting of S2. Lung examination is unremarkable.
A transthoracic echocardiogram demonstrates a normal size left ventricle with ejection fraction of 65% and right ventricular enlargement. The estimated pulmonary artery systolic pressure is 58 mm Hg. Spirometry, lung volumes, and ventilation-perfusion scan are unremarkable; DLCO is 42% of predicted. CT angiogram of the chest is negative for pulmonary embolism and interstitial lung disease. Right heart catheterization demonstrates a mean pulmonary arterial pressure of 36 mm Hg, with no change with inhaled nitric oxide. Pulmonary capillary wedge pressure is normal.
Which of the following is the most appropriate treatment?
A. Bosentan
B. Diltiazem
C. Metoprolol
D. Pirfenidone
MKSAP Answer and Critique
The correct answer is A. Bosentan. This content is available to MKSAP 18 subscribers as Question 46 in the Pulmonary and Critical Care Medicine section. More information about MKSAP is available online.
The most appropriate treatment is bosentan. This patient has pulmonary hypertension most consistent with Group 1 (pulmonary arterial hypertension [PAH]), based upon the right heart catheterization demonstrating high pulmonary arterial pressures in the absence of left-sided heart failure, lung disease, and venous thromboembolic disease. Before administering advanced therapy for patients with PAH, vasoreactivity testing with nitric oxide is performed to identify those who may respond to calcium channel blockers (CCBs). CCBs are desirable therapy because they are less expensive and have fewer side effects than other forms of advanced therapy. Failure to achieve a favorable hemodynamic response with nitric oxide predicts unresponsiveness to CCBs and the need for other advanced therapy. The endothelin receptor antagonist bosentan is one of many oral pulmonary vasoactive drugs that is indicated in PAH in patients with negative vasoreactivity testing, such as this patient, some of which have been shown to increase exercise capacity and improve echocardiographic parameters.
CCBs such as diltiazem may be used in the setting of PAH when a response to a vasodilator such as nitric oxide is demonstrated during right heart catheterization. When a response is not found, CCBs are not indicated.
β-Blockers such as metoprolol do not have a proved role specific to PAH, though they might be used as an adjunct agent for supraventricular tachyarrhythmias that are common in this population.
Pirfenidone is an antifibrotic agent indicated for the treatment of idiopathic pulmonary fibrosis. Pulmonary hypertension is frequently observed in patients with idiopathic pulmonary fibrosis, but pirfenidone would not be indicated for a patient with PAH without idiopathic pulmonary fibrosis.
Key Point
- Before administering advance therapy for patients with pulmonary arterial hypertension (PAH), particularly idiopathic PAH, vasoreactivity testing directs agent selection by identifying those who may respond to calcium channel blockers.